Abstract

Use of coded signals for acoustic wind profiling presents special challenges because the scattering mechanism is highly bandwidth sensitive. We outline the physical principles involved and show that the signal coding methods commonly used for underwater acoustics or for transmission in the atmosphere such as for tomography do not apply for scattering of sound by turbulence. The degree of
detuning and loss of signal strength is examined for FM chirps, in relation to the corresponding increase in signal-to-noise ratio (SNR)from matched filters. The optimum bandwidth does not give a large improvement in SNR for this physical situation. The alternative, and very conventional, use of stepped frequency chirps is examined in comparison. This too requires special consideration as to the length
of each constant-frequency part. Finally, we give some insight into future developments using a combination of these approaches.